A raft of questions remain over how two people were poisoned with a nerve agent in the UK. 

The pair are still in hospital after coming into contact with Novichok, the same agent used in the attack on the Skirpals in March.

It is thought they came into contact with the remnants of the first batch of poison. 

However, UK correspondent Gavin Grey says that theory's starting to lose water. 

"In the open air with the rain and the wind, how on earth were these people contaminated and they're both critically ill in hospital so many weeks later?" 

LISTEN ABOVE AS GAVIN GREY SPEAKS WITH TIM DOWER.